events {
    worker_connections 1024;
}

http {
    upstream phoenix_backend {
        least_conn;
        server phoenix1:4000 max_fails=3 fail_timeout=30s;
        server phoenix2:4000 max_fails=3 fail_timeout=30s;
        server phoenix3:4000 max_fails=3 fail_timeout=30s;
    }

    # Map to track which backend server a WebSocket connection should use
    map $http_upgrade $connection_upgrade {
        default upgrade;
        '' close;
    }

    server {
        listen 4000;
        server_name localhost;

        # WebSocket configuration
        location /socket {
            proxy_pass http://phoenix_backend;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection $connection_upgrade;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            # WebSocket timeout settings
            proxy_read_timeout 86400;
            proxy_send_timeout 86400;
        }

        # HTTP fallback for health checks
        location / {
            proxy_pass http://phoenix_backend;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }
    }
}